Merge #2716

2716: Allow assists with multiple selectable actions r=SomeoneToIgnore a=SomeoneToIgnore

This PR prepares an infra for rust-lang/rust-analyzer#2180 task by adding a possibility to specify multiple actions in one assist as multiple edit parameters to the `applySourceChange` command.

When this is done, the command opens a selection dialog, allowing the user to pick the edit to be applied.

I have no working example to test in this PR, but here's a demo of an auto import feature (a separate PR coming later for that one) using this functionality:

![out](https://user-images.githubusercontent.com/2690773/71633614-f8ea4d80-2c1d-11ea-9b15-0e13611a7aa4.gif)

The PR is not that massive as it may seem: all the assist files' changes are very generic and similar.

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>

rust-analyzer/editors/code/src/commands/index.ts

@@ -39,6 +39,18 @@ function applySourceChange(ctx: Ctx): Cmd {
     };
 }
 
+function selectAndApplySourceChange(ctx: Ctx): Cmd {
+    return async (changes: sourceChange.SourceChange[]) => {
+        if (changes.length === 1) {
+            await sourceChange.applySourceChange(ctx, changes[0]);
+        } else if (changes.length > 0) {
+            const selectedChange = await vscode.window.showQuickPick(changes);
+            if (!selectedChange) return;
+            await sourceChange.applySourceChange(ctx, selectedChange);
+        }
+    };
+}
+
 function reload(ctx: Ctx): Cmd {
     return async () => {
         vscode.window.showInformationMessage('Reloading rust-analyzer...');
@@ -59,5 +71,6 @@ export {
     runSingle,
     showReferences,
     applySourceChange,
+    selectAndApplySourceChange,
     reload
 };

rust-analyzer/editors/code/src/main.ts

@@ -26,6 +26,7 @@ export async function activate(context: vscode.ExtensionContext) {
     ctx.registerCommand('runSingle', commands.runSingle);
     ctx.registerCommand('showReferences', commands.showReferences);
     ctx.registerCommand('applySourceChange', commands.applySourceChange);
+    ctx.registerCommand('selectAndApplySourceChange', commands.selectAndApplySourceChange);
 
     if (ctx.config.enableEnhancedTyping) {
         ctx.overrideCommand('type', commands.onEnter);